The present invention relates to an apparatus and a method for removing a coating at a desired position from a coated linear material having a coating layer on a core material, such as a coated optical fiber having a coating layer on glass optical fiber.
Optical fiber glass for optical communication is a fragile material having a very small outer diameter of about 125 .mu.m, so that it is susceptible to influences of mechanical stress and the environment. To protect the glass optical fiber from these influences, glass optical fiber is provided with a coating of a macromolecular material such as silicone, urethane or the like.
In the case where branching of a coated optical fiber or the like is to be carried out in an optical line constituted by a coated optical fiber having a coating layer on glass optical fiber, the coating layer need be removed from the coated optical fiber at a desired position of the coated optical fiber.
As one conventional coating removing technique, an "optical fiber coating removing apparatus" has been disclosed in Japanese Utility Model Unexamined Publication No. Hei-2-3502. This is a technique for removing a coating layer from a coated optical fiber by placing the coated optical fiber in a slot formed by a pair of upper and lower coating removing jigs, bringing blades into contact with the coating layer of the coated optical fiber at sharp angles, and moving the blades relative to the coated optical fiber.
FIG. 15 is a view for explaining the condition of use of an example of the optical fiber coating removing apparatus as disclosed in the above Japanese Utility Model Unexamined Publication No. Hei-2-3502. The coated optical fiber A is placed in grooves 03a and 04a of a pair of upper and lower coating removing jigs 03 and 04. Upper and lower blades 01 and 02 fixed to the jigs are in contact with the coating layer of the coated optical fiber A at sharp angles from upper and lower directions in symmetric positions on the axis of the coated optical fiber A and in a direction perpendicular to the axis of the coated optical fiber A. In this condition, the coating layer is removed by moving the coated optical fiber A in the direction of the arrow a in the drawing or by moving the coating removing jigs in the reverse direction.
In the aforementioned conventional coating removing apparatus, the contact position between the cutting blades and the coated optical fiber is always constant, so that it is sometimes necessary to replace the cutting blades by new ones or polish the edges of the blades. Whenever the cutting blades are replaced or the edges thereof are polished, the positions of the edges of the blades must be adjusted so as to be symmetric by adjusting the distance between the edges of the blades with respect to the coated linear material. Because the coated optical fiber has a particularly small diameter d of 125 .mu.m, the adjustment is troublesome. Accordingly, much labor is required for the adjustment whenever the blades are replaced or the edges thereof are polished. Consequently, this is inconvenient in use when repeated daily. Furthermore, it is most difficult to adapt the adjustment to the blades through the entire lengths of the edges of the blades, and it is impossible to use the whole edges of the blades effectively.